1. Field of the Invention
The invention is directed to an improved method for sheathing an armature for electrical machines, in which a lamination that has slots for armature windings is slipped with a bore onto an armature shaft and provided by means of the sheathing with at least one slot insulation. The plastic flows through gates which extend along the bore of the lamination packet and along the surface of the armature shaft.
2. Description of the Prior Art
Armatures of permanent-magnet-excited small electric motors have lamination packets comprising individual laminations, or lamination packets ready for installation, which are fixed in various ways to the respective armature shafts. Besides fixation using plastic deformation (as in German Patent Disclosure DE 19933037 A), bolts (see French Patent Disclosure FR 2644947), by pressing onto knurled armature shafts, and so forth, fixation by end feeding, or sheathing, is also known. In sheathing processes by the hot-gate molding technique, with PAA6.6, minimal slot insulation wall thicknesses of 0.4 to 0.7 mm over a lamination packet length of approximately 30-40 mm are currently possible in large-scale mass production.
Furthermore, stamping packets with bores for cooling (as in Japanese Patent Disclosure JP 2000152527) or for injecting a slot insulation in the form of leadthrough gates in the injection-molding plastic are known.
The lamination geometry depends on production requirements, such as linking capability, orientation capability, and magnetic flux (see for instance JP 2003164080 or JP 2002165392).